Generally, the airbag apparatus for a vehicle is constructed in such manner that, when the vehicle has been subjected to an external impact, it inflates the airbag, with gas emitted from an inflator, to thereby lessen or cushion the impact applied to a vehicle occupant. Japanese Laid-Open Patent Publication No. HEI-6-1188 discloses an airbag apparatus which has a plurality of inflating chambers formed via a strap with a view to achieving an enhanced strength of the inflated airbag.
The airbag apparatus disclosed in the HEI-6-1188 publication will be explained below with reference to FIG. 18.
The airbag apparatus of FIG. 18 includes a bag body 301 disposed inside a door adjacent to a driver's seat. The bag body 301 includes an upper cloth 302 and lower cloth 303 that are sewn together, with a strap 304 interposed therebetween, to secure an increased strength. More specifically, the upper cloth 302 and lower cloth 303 are sewn together to form a plurality of inflating chambers 306, 307, 308, 309 and 311, which are in fluid communication with one another through communicating holes 312, 313, 314 and 315 formed in the strap 304.
In the bag body 301, the individual chambers 306, 307, 308, 309 and 311 can be instantly filled with gas emitted from an inflator 316 through the communicating holes 312, 313, 314 and 315, but it is necessary to provide a great-size airbag opening portion through which the bag body 301 to be developed can jump out of the door into the interior of the vehicle, and provide a great-size lid for the airbag opening portion. However, design freedom would be considerably limited if the airbag opening portion and lid are formed into great sizes, particularly in the case of a curtain airbag apparatus provided on a vehicle roof or a side airbag apparatus provided on a vehicle door. Further, if the airbag opening portion and lid are formed into great sizes, it would be difficult to secure sufficient strengths of interior members, such as resin-made door linings.